Patent Literature No. 1 discloses a technique of spraying a viscous absorbing liquid which has been reserved in a tray disposed above heat transfer pipes from the tray toward the heat transfer pipes by gravity, thereby placing the absorbing liquid on the heat transfer pipes and cooling the absorbing liquid on the heat transfer pipes, and contacting the absorbing liquid and vapor, thereby allowing the absorbing liquid to absorb the vapor, in a liquid spray device of an absorption water cooler-heater. Patent Literature No. 2 discloses a technique of uniformly diffusing and mixing liquid to be dropped on coating surfaces of heat transfer surfaces by a blade or a brush, thereby increasing effective heat transfer area of the liquid, in an absorber of an absorption refrigerator.    Patent Literature No. 1: Japanese Unexamined Patent Publication No. 2000-179989    Patent Literature No. 2: Japanese Unexamined Patent Publication No. H4-236079